DIY elektrostatiske hovedtelefoner



DIY elektrostatiske hovedtelefoner

Indlægaf Boegebjerg » 26. nov 2016, 07:51

Nu fik jeg jo lyttet lidt til et par Stax 007'er til meetet i København, og var godt nok noge målløs over hvor godt de lød. Har længe gået med en drøm om at lave mine egne elektrostatiske hovedtelefoner, og det her skubbede mig over the edge, så jeg har bestilt alle materialer til at lave et par drivere selv.

For omkring et halvt ĂĄrs tid siden faldt jeg over nogle DIY hovedtelefoner af en gut som kalder sig Chinsetta Wong pĂĄ Head Fi. Han har lavet noget utroligt vellydende elektrostatiske hovedtelefoner, sĂĄ jeg har ladet mig inspirere af ham.

Her er frekvens responsen for hans Orpheus clone
Billede

vs Sennheiser HD800
Billede

Orpheus clone distortion
Billede

vs Sennheiser HD800 distortion
Billede


Som I kan sig klare den sig ret godt selv nĂĄr den er sat op mod en af de store drenge. SĂĄ siger jeg det bare lige igen, det her er DIY.


Som stator har jeg valgt at bruge 1mm kobber belagt glasfiber PCB, som jeg har bestilt hjem fra Kinaland.
Jeg har ogsĂĄ bestilt noget 0.5mm glasfiber PCB, som jeg vil bruge som spacer.
Til diaphragm har jeg bestilt noget super tyndt Mylar, 0,002mm. Det skulle være et super stærkt stykke film. Har godt nok brugt en del tid på at finde det her mylar. Det fås i mange forskellige udgaver og tykkelser. De fleste steder vil de helst have man køber et par hundrede meter ad gangen, men har endelig fundet et sted i England hvor man kan få nogle mindre stykker til overkommelige priser.
Man skal belægge den her diaphragm med noget strømledende. Er ikke helt sikker på hvad der virker bedst, så jeg har blot bestilt noget graphite pulver, da jeg har læst at nogle anvender det. Det bliver nok skiftet ud på et tidspunkt.
Til at holde det hele sammen med har jeg bestilt noget kontakt cement fra Israel.

Jeg har adgang til CNC maskiner igennem universitetet, sĂĄ kan nok opnĂĄ nogle rimelige tolerancer.
Har læst at noget af det sværeste er at stramme filmen op så den er lige stram over hele overfladen. Der er en del forskellige DIY rigs til at spænde film, så må se hvad jeg kan finde til at lave den med.

HĂĄber jeg ender med en stabil driver. musik17


Er der nogle som har erfaring med at lave elektrostatiske hovedtelefoner / højtalere?
Nogle tips eller tricks?
Boegebjerg

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Re: DIY elektrostatiske hovedtelefoner

Indlægaf Peter Jensen » 26. nov 2016, 10:33

Lyder sindssygt spændende og ambitiøst (på den gode måde...). Glæder mig til at følge med i hvordan det går.... popsy
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Re: DIY elektrostatiske hovedtelefoner

Indlægaf Claus-DK » 26. nov 2016, 11:15

Det er da noget af et projekt, jeg følger dette meget tæt og ser frem til mere mere mere mere....
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Re: DIY elektrostatiske hovedtelefoner

Indlægaf Solderdude » 27. nov 2016, 11:05

I have plenty of experience building electrostatic speakers.
These, however, have a neat trick where the membranes are not tensioned at all.

For headphones there are a few things to watch out for.
First ... you will have a few hundred volts close to your head... be carefull ... isolate !
Second... the skin around your ears will sweat... moisture and high voltages don't go well together... sparking and holes in the membrane !

Then there is the interaction between driver and pads... pads can make or break the sound of any good driver !

Also you need a good 'energiser'.
This last bit is what kept me from stats ... no mobility which is important to me.

Agreed though ... you can create a fantastically good sounding speaker or headphone yourself !
And stats can have something 'magical' to it.

Other points:
Tensioning and above all keeping it tensioned is of great importance here.
It MUST be done with the perfect tension otherwise the results will be below par.
The amount of tension depends on the thickness and material used.
Mylar is probably the best suited material as it keeps tension the best over time.

Making it conductive is a bit difficult but graphite powder does work.
For Mylar it takes a LOT of rubbing to work it in there but can be done.
Fortunately the membrane doesn't have to conduct really well... when you reach 1MOhm it is already enough.
The reason for this is... no current (except while charging).
Make contact with the membrane over the entire ring... better than a small spot for sure.
When working with graphite powder watch out for small 'chunks' .
These can tear through the membrane when applying too much force.
I recommend to rubbing it in there using a dab of cotton.
Make sure to wipe it 'clean' when done.
You DON'T want particles to collect on your isolator and form a 'spark bridge' there.

Success ! I really mean it, the results can be great but to get there may take many drivers and experiments.
Just copying a 'known' design is not a guarantee to success.

Maybe one day I might even try to make one for myself.
Use your ears to enjoy music, not as an analyzer.
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Re: DIY elektrostatiske hovedtelefoner

Indlægaf Boegebjerg » 28. nov 2016, 12:34

Solderdude skrev:I have plenty of experience building electrostatic speakers.
These, however, have a neat trick where the membranes are not tensioned at all.

For headphones there are a few things to watch out for.
First ... you will have a few hundred volts close to your head... be carefull ... isolate !
Second... the skin around your ears will sweat... moisture and high voltages don't go well together... sparking and holes in the membrane !

Then there is the interaction between driver and pads... pads can make or break the sound of any good driver !

Also you need a good 'energiser'.
This last bit is what kept me from stats ... no mobility which is important to me.

Agreed though ... you can create a fantastically good sounding speaker or headphone yourself !
And stats can have something 'magical' to it.

Other points:
Tensioning and above all keeping it tensioned is of great importance here.
It MUST be done with the perfect tension otherwise the results will be below par.
The amount of tension depends on the thickness and material used.
Mylar is probably the best suited material as it keeps tension the best over time.

Making it conductive is a bit difficult but graphite powder does work.
For Mylar it takes a LOT of rubbing to work it in there but can be done.
Fortunately the membrane doesn't have to conduct really well... when you reach 1MOhm it is already enough.
The reason for this is... no current (except while charging).
Make contact with the membrane over the entire ring... better than a small spot for sure.
When working with graphite powder watch out for small 'chunks' .
These can tear through the membrane when applying too much force.
I recommend to rubbing it in there using a dab of cotton.
Make sure to wipe it 'clean' when done.
You DON'T want particles to collect on your isolator and form a 'spark bridge' there.

Success ! I really mean it, the results can be great but to get there may take many drivers and experiments.
Just copying a 'known' design is not a guarantee to success.

Maybe one day I might even try to make one for myself.



Hear ya on the portability! I will need an amp / energizer for this. I'm looking around for cheap options right now. Do you know *how* important it is to get a really good one? I was thinking of just buying the cheapest I could find. The most important thing is that I have to be able to play around with the bias voltage. This will of course require some modding, but I assume I can figure out how to change the bias.

Speaking of bias. This is really the only point I'm unsure of. *How* do I charge the diaphragm? I assume I have to lead a cable to touch the diaphragm, but is "cable-touches-diaphragm" enough, or should I lead it all the way around the edge, so it is charged from all sides? That might wreck havoc on my tolerances.

I'm going into this with the expectation that I'll fail, but I'll keep on trying 'til I get it right and make something that works -- even if it will take me years.

I plan on spending most of my time working on a good tensioning rig. This is definitely the make it or break it, so naturally my focus lies here.

Thanks for your input!


Oh hey, tak for interessen thumbs Det hjælper rigtig meget på motivationen at andre finder projektet spændende 9musik
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Re: DIY elektrostatiske hovedtelefoner

Indlægaf Solderdude » 28. nov 2016, 16:21

The bias is important, so is the audio high voltage supply.

The audio high voltage supply must be able to deliver a high voltage. Little current is needed for low frequencies but higher current is needed for higher frequencies.
With great transient speed thus comes current. This is because the capacitor (the 2 stators and headphone cable) need to be charged and discharged quickly.

First experiments can be done with a transformer (toroid) with a centertap.
When it is coming along a 'real' amplifier (tube or SS) will be needed for lower distortion.

The bias is another important thing. Too little of it = distortion, too much of it = hiss and possible pin holes in the membrane due to arcing.
The higher the bias voltage the louder it will play as well.
The stator-membrane difference determines the proper bias voltage.
There are rules for this.

Making the high bias voltage is easy.. I suggest to use a step up transformer in order to galvanically separate.
Also easy to change the bias voltage. Simply a matter of using a voltage multiplier and using different 'taps'.
The high voltage should be supplied through a resistor (1 MOhm or so) and is present between the diafragm and both stators (the stators have the same potential for the bias)
plenty of schematics floating about for a simple energizer with a transformer and high voltage supply using a voltage multiplier.
At head-fi and DIY audio there will be lots of info on this I presume.

because the mylar is rather difficult to make conductive I recommend to make a thin 'ring' of aluminium foil which is connected to the bias tap.
The membrane's conductive side is then tensioned over that ring (as much as possible contact) and glued down.
I don't recommend making a small contact because at that point the conductive stuff can 'arc' away causing the membrane not to be charged any more.
Use your ears to enjoy music, not as an analyzer.
Solderdude

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Re: DIY elektrostatiske hovedtelefoner

Indlægaf mikkelmmk93 » 1. dec 2016, 14:51

Jeg følger lige spændt med her :D
Denon AH-D2000
ODAC
DIY O2 - viewtopic.php?f=12&t=5838
DIY CIEM - på vej. Følg udviklingen her: viewtopic.php?f=12&t=5793
mikkelmmk93

 
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Re: DIY elektrostatiske hovedtelefoner

Indlægaf Boegebjerg » 20. dec 2016, 08:41

Har modtaget alt udover grafitpulveret. ForhĂĄbenlig kommer det i dag eller i morgen sĂĄ jeg kan komme i gang i juleferien.
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